The rate at which airbags have been installed in automobiles as safety equipment has improved rapidly. These airbags protect the bodies of passengers by preventing the bodies of passengers from colliding with interior vehicle components, walls or glass by being rapidly inflated with high-pressure gas from an inflator to allow the gas to cause the airbag to be deployed at a high speed at the time of an automobile accident involving a collision. In recent years, there has been a growing need in the automobile industry to increase the deployment speed of airbags following an automobile collision from the viewpoint of improving passenger protection.
In addition, this type of safety equipment has been expanded to include side bags and side curtains from the viewpoint of side-protecting for passengers. These side curtain bags are required to prolong the time the bag is maintained in a deployed state, or in other words, improve internal pressure retention, in order to reduce impacts applied to passengers during a rollover from the viewpoint of improving passenger safety during an accident involving a vehicle rollover. Consequently, the usage rate of resin-coated base fabrics (coated with materials containing substances known as elastomers) that reduce air permeability is increasing for use as airbag base fabric.
The air permeability of base fabrics has previously been reduced by increasing the amount of coated resin in order to obtain a coated base fabric having superior internal pressure retention. However, the coated surfaces end up adhering and have difficulty separating due to the adhesiveness of the resin. Although airbags are folded before being housed in an automobile, since coated surfaces adhere to each other at that time, this hinders the smooth inflation of the airbags at the time of deployment.
In addition, when sewing the base fabric, work ends up being interrupted each time coated surfaces make contact due to the high level of adhesiveness of the resin coated on the base fabric, thereby resulting in the occurrence of decreases in working efficiency and workability.
In order to prevent this adhesion, the following Patent Document 1 discloses that deployment properties are improved by adding a lubricant and inorganic compound to a coating agent or forming a fine pattern of surface irregularities on a silicone surface. However, this has the shortcoming of making the processing process complex.
Moreover, since airbag base fabrics easily become electrostatically charged, in addition to being difficult to handle during processing, there was also concern over the static electricity having a detrimental effect on automobile electronic control equipment when installed in an automobile. Patent Document 2 indicates that a base fabric consisting of silicone coated onto a Nylon 66 base fabric demonstrates higher charging properties than uncoated base fabric. This is thought to be due to the nylon and silicone being positioned at both poles of an charging series. Patent Document 2 discloses a method for controlling electrical charge with the seam of the base fabric by using an electrically conductive suturing thread. In addition, Patent Document 3 discloses a method for controlling electrical charge by blending an electrically conductive thread when weaving the base fabric. However, not only is the use of a special electrically conductive thread economically unsuitable, since fibers containing an electrically conductive substance have different properties with respect to mechanical properties and the like, there is the problem of the creation of mechanical weakness.
At present, there are no known airbags or airbag base fabrics that are able to solve the aforementioned problems and demonstrate superior deployment speed, internal pressure retention and workability.